gerhart



March 17, 1964 R. T. GERHART 3,125,331

DIE CONSTRUCTION Filed Sept. 10, 1962 w T w b u, n 31 33 INVENTOR. ROLAND 7. GERHART ATTORNE United States Patent 3,125,331 DIE CONSTRUCTION Roland T. Gerhart, West Bloomfield Township, Oakland 1(\l loullllgy, Mich. (5218 Doherty Drive, Orchard Lake,

Filed Sept. 10, 1962, Ser. No. 222,328 1 Claim. (Cl. 267-1) This invention relates to a die construction for a press and, more particularly, relates to a spring-type stripper structure which includes means for preventing a broken spring from causing damage to the die parts. I,

It is common practice in die design to provide structure connecting two die parts for limited relative movement with respect to each other and to provide resilient means to urge these parts away from each other. For example, it is conventional practice to connect a bolt to a movable stripper plate or pressure pad with the head of the bolt being placed in a suitably shaped recess in a stationary die shoe, the bolt being slidable within the recess to a limited extent until the head thereof engages a shoulder in the recess. In one such construction, a coil spring coaxially encircles the bolt and urges the two die parts away from each other. While such structures are generally satisfactory, problems have been encountered therewith. Particularly, where the die parts can move relative to each other only a small distance and the confronting faces of the two die parts are intended to be moved close to or even into contact with each other, there is a serious problem of obtaining proper mounting and positioning of the parts of the stripper structure. Further, since the spring eventually will break during use of the die construction, if one of the broken ends of the spring should come between the confronting faces of the die parts, it is likely that one of the die parts, usually the pressure pad or stripper plate, will be broken when the die parts are next moved toward each other. This will involve substantial repair expense and, further, results in loss of production time for the press involved.

Accordingly, it is an object of this invention to provide an improved die construction for a press, which die construction has a stripper bolt connecting two die parts for permitting limited relative movement therebetween and a spring surrounding the bolt and urging the die parts away from each other, the spring being confined within a cage so that no part of the spring can come between the confronting faces of the die parts.

It is a further object of this invention to provide an improved retainer structure connecting the head of a stripper bolt for limited sliding movement with respect to a die part, the retainer structure including a cage for confining a spring 'so that no part of the spring can come between the confronting faces of the die parts.

It is a further object of this invention to provide an improved retainer structure, as aforesaid, which consists of a few, relatively simple parts, which is inexpensive to manufacture and which can be mounted in or removed from the die parts easily and without requiring complete disassembly of the die construction.

Other objects and advantages of the invention will become apparent to persons acquainted with equipment of this type upon reading the following description and inspecting the accompanying drawings.

In the drawings:

FIGURE 1 is a central sectional view of a fragment of a die construction and showing structure embodying the invention.

FIGURE 2 is a sectional view taken along the line IIII of FIGURE 1 with the stripper bolt removed.

Referring to the drawings, the die construction comprises a pair of die parts 11 and 12 which have similar, aligned recesses 13 and 14 in the confronting faces 16 and 17 thereof. The die part 12 ordinarily is a movable pressure pad or stripper plate while the die part 11 ordinarily is a stationary die shoe. In FIGURE 1, the die parts 11 and 12 are shown in a spaced apart relation. In use, the die part 12 can be moved toward the die part 11 to a position in which the surfaces 16 and 17 are close to or are contacting each other.

A stripper bolt 21 has a threaded portion 23 on the shank 22 thereof and said threaded portion is threaded into a threaded hole 24 in the base wall 20 of the recess 13. A shoulder 26 between the threaded portion 23 and the unthreaded portion of the shank 22 abuts against the base wall 20 of the recess 13.

A retainer structure 27 is seated against the base Wall 25 of the recess 14 and said retainer structure includes an upstanding, substantially cylindrical, cap portion 28 within which the head 29 of the bolt 21 is slidably disposed. The cap portion 28 has an inturned, reversely bent flange 30 at its upper end against which the head 29 of the bolt 21 abuts when the die parts 11 and 12 are in their spaced apart relation as shown in FIGURE 1. The flange 30 provides a central opening 31 through which the shank 22 of the bolt 21 closely slidably extends.

The cap portion 28 has a plurality, here four, of radially outwardly extending, circumferentially spaced, substantially coplanar flanges 32 at its lower end which rest on the base wall 25 of the recess 14. A spring cage 33 has a radially inwardly extending flange 34. The flange 34 has an upwardly offset, inner edge portion 36 which overlaps the flanges 32 and is secured thereto, as by welding. The radially outermost portion of flange 34 is substantially coplanar with the flanges 32 and it rests against the base wall 25 of the recess 14.

The spring cage 33 has a substantially cylindrical wall 37 which extends upwardly from the flange 34 through the recess 14 and into the recess 13. It is to be noted that the distance a between the upper end of wall 37 and the base wall 20 of recess 13 is greater than the distance b between the confronting surfaces 16 and 17 of the die parts 11 and 12 so that said surfaces can move into contact with each other without interference. The diameter of the Wall 37 is less than the diameter of the recesses 13 and 14 so that said wall normally is spaced from the side walls of said recesses.

A coil spring 41 is disposed within the wall 37 of the spring cage 33. The upper end of the coil spring 41 bears against the base Wall 20 of the recess 13 and the lower portion of the coil spring 41 extends through the annular space between the wall 37 and the cap portion 28. The lower end of the spring 41 bears against the flange 34. This spring 41 is compressed continuously. Thus, the spring 41 releasably holds the retainer structure 27 and the spring cage 33 in the recess 14 and said spring urges the die part 11 away from the die part 12. The die open" or preload spring pressure may be entirely confined by the stripper bolt 21, thus relieving the pounding shock forces on the retainer structure 27. The spring 41 is confined within the spring cage 33 so that if the spring should break, it would not be possible for any part of the spring 41 to come between the confronting surfaces 16 and 17 of the die parts. Thus, damage to the die parts 11 and 12 which might result from breakage of the spring 41 is prevented. Moreover, it is not necessary to fixedly secure the retainer structure 27 and the cage 33 in the recess 14 because the spring 41 holds same in place.

The spring cage 33 will not interfere with the desired movement of the die parts 11 and 12 but it will prevent damage thereto if the spring should break. The retainer structure 27 and the spring cage 33 can be formed of sheet metal parts and, thus, can be manufactured at low cost. Mounting and demounting of the spring cage 33 and the retainer structure 27 can be effected easily by moving the die parts 11 and 12 far enough apart to permit the bolt 21 to be engaged by a tool, such as a screw driver, whereby the bolt can be threaded into or unthreaded from the die part 11.

The operation of the die parts 11 and 12 will follow conventional practice and, hence, a detailed description thereof is believed to be unnecessary.

While a particular preferred embodiment of the invention has been described, the invention contemplates such changes or modifications therein as lie within the scope of the appended claim.

What is claimed is:

A die construction comprising:

a pair of die parts mounted for limited relative movement with respect to each other, said die parts having mutually confronting surfaces having aligned recesses therein;

a bolt secured to one die part and extending perpendicularly from the base wall of the recess therein toward the base wall of the recess in the other die part, said bolt having a head adjacent to said other die part;

a retainer structure mounted in the recess in said other die part and including a tubular cap portion extending perpendicularly to the base wall of the recess in said other die part, said cap portion having an inturned flange at the end thereof which is adjacent 4 to said one die part, the head of said bolt being slidably received within said cap portion and being engageable with said flange to limit movement of said one die part away from said other die part;

a tubular spring cage secured at one end thereof to said retainer structure and received within said recess in said other die part, said spring cage extending into the recess in said one die part and being spaced from the base wall in said recess in said one die part a distance greater than the distance between said confronting surfaces when said bolt head engages said inturned flange, said spring cage being coaxial with and spaced radially from said cap portion to provide an annular space therebetween; and

a coil spring encircling said cap portion and said bolt and received in said annular space, one end of said spring engaging the base wall in said recess in said one die part and the other end of said spring engaging said retainer structure and spring cage and holding same within the recess in said other die part.

References Cited in the file of this patent UNITED STATES PATENTS 1,022,225 Chabot Apr. 2, 1912 1,811,987 Wales June 30, 1931 1,961,634 Faunton June 5, 1934 2,324,657 Wales July 20, 1943 2,579,641 Aldrich Dec. 25, 1951 2,815,200 Gerhart et a1. Dec. 3, 1957 

